So, does the GF offer measurably better accuracy than others? Does it offer measurably better longevity than others?
This data is unlikely to ever exist in a measurable, repeatable form. I would hazard that beyond a certain level of finishing is makes no difference to the tribological performance. Instead, the finish is an expression and example of human effort. Which is I guess what makes it valued.
I actually prefer the precision machined finish of a GS, as I find too much decoration a little fey. IMHO of course.